Stud-bonding gun

ABSTRACT

A tool for mounting and removing studs having an adhesive coated head portion and a stem extending therefrom. The tool includes an outer housing with attached handle and a stud-receiving means mounted in the housing. The stud-receiving means includes a heater for softening the adhesive on the stud, a locking device for releasably holding the stud in the tool and ejection means for ejecting the stud toward a mounting surface when the locking means is released by closing a trigger switch. Electrical contact elements mounted in the housing are actuated when pressed against the mounting surface. The contact elements are connected in series with the trigger switch to prevent release of the locking means unless the contact elements are properly actuated. This assures proper positioning of the tool with respect to the mounting surface. A heat-sensing device is provided for monitoring the temperature of the stud head portion.

United States Patent [72] Inventors William G. Simpson;

Bllly K. Devin, both of Huntsville, All. [21 Appl. No. 889,437 [22]Filed Dec.3l,1969 [4S] Patented July 13, 1971 [73] Assignee The UnitedStates of America as represented by the Adminbtrntor of the NationalAeronautics and Space Administration [54] STUD-BONDING GUN 9Clnims,7Drawing Figs.

[52] U.S.C1 219/243, 156/66, 156/320, 219/221 [51] Int-Cl H051! H00 [50]Field 0! Search 219/243, 221, 228, 230, 237, 245, 240;156/66, 306, 320,502

[56] Reierences Cited UNITED STATES PATENTS 2,681,685 6/1954 Arkless219/227 2,942,096 6/1960 Jones... 219/98 3,281,576 10/1966 Cooper et a1219/421 32 ts. :27. N i 60 i b i 34 6 "11;" :1

l l :..:1 .1 1 l 74 N s :zzzj 3,005,421 10/1961 Lea.

OTHER REFERENCES IBM TECHNICAL DISCLOSURE Epoxy Curing Tool," Vol.9 No.10, March 1967 ABSTRACT: A tool for mounting and removing studs havingan adhesive coated head portion and a stem extending therefrom. The toolincludes an outer housing with attached handle and a stud-receivingmeans mounted in the housing. The stud-receiving means includes a heaterfor softening the adhesive on the stud, a locking device for releasablyholding the stud in the tool and ejection means for ejecting the studtoward a mounting surface when the locking means is released by closinga trigger switch. Electrical contact elements mounted in the housing areactuated when pressed against the mounting surface. The contact elementsare connected in series with the trigger switch to prevent release ofthe locking means unless the contact elements are properly actuated.This assures proper positioning of the tool with respect to the mountingsurface. A heat-sensing device is provided for monitoring thetemperature of the stud head portion.

PATENTED JUL 1 319m SHEET 1 BF 2 III! Fig. 6

INVEN TOR Biliy K. Davis William G. Simpson BY (,0?

M C ATTOHNF Y5 STUD-BONDING GUN ORIGIN OF THE INVENTION The inventiondescribed herein was made by employees of the United States Governmentand may be manufactured and used by or for the Government forgovernmental purposes without the payment of any royalties thereon ortherefor.

BACKGROUND OF THE INVENTION The invention is a tool for bonding studs ofvarious types to a surface. More particularly it is a tool which makesit possible to mount and/or remove a stud from a surface withoutaltering or defacing the mounting surface.

The time is rapidly approaching when men will be either fabricating ormodifying various structures in the zero gravity environment of space.To accomplish this a number of new tools have or will be developed; someuseful only in space, but many also useful in a terrestrial environmentwhere gravity forces are present. The present invention falls in thislatter group since it will be useful here on earth even though designedspecifically for zero gravity operation. Some features of a space toolmight be altered somewhat if it were going to be used only on earth. Forexample, the handle of the tool described herein has been made verylarge and roomy so as to easily accommodate the gloved hand of anastronaut. Also the handle has been designed so that no rotationaltorque will be generated "Zen a stud is ejected from the gun. The firstexperimental prototype built had a simple pistol grip, which made thetool cheaper to construct and adequate for use on earth where the useris firmly anchored because, due to gravity, he has weight. A space-ratedtool however, requires an improved handle. This brief discussion is notan attempt to attach particular significance to the tool handle, but isintended only to point out that tools for space may have expensivespecial requirements not present in tools for terrestrial use. Actually,handle design is one of the more simple and straightforward features tobe considered in designing a tool for an astronaut.

It can be appreciated that in most construction operations various typesof studs can be put to good use in mounting arrangements and in makingconnections. For example, space station equipment such as TV cameras,workshop-type tools, lights, and wiring harnesses associated with suchequipment, could be stud mounted. Studs will facilitate extra-vehicularactivity when used to fasten mooring lines or attachment rings to theouter surface of the space station. Equipment and supplies can bepositioned outside the vehicle and lashed down to one or more studs.Telescopes, solar cell panels and antennas could be fastened to theouter surface of a space station with studs. The listing could go on toinclude almost anything which required mounting or attaching.

For down-to-earth applications the tool could be used to apply studs toaircraft and other vehicles for mounting added equipment. This could besimpler than drilling and/or tapping holes in the mounting surface. Inpublic buildings, particularly those having walls of marble or otherexpensive coverings, removable studs could be used for hanging picturesor signs so that subsequent changes will not result in the wall beingdefaced. Methods of mounting studs heretofore have usually included anactual insertion of the stud into the wall. In instances where the studwas applied to a wall or workpiece by adhesives. the wall or workpiecewas heated. Heating the workpiece is often difficult and sometimesprohibited if the workpiece is heat sensitive.

SUMMARY OF THE IN VENTION The object of the invention is to provide atool for mounting and removing adhesively bonded studs from a surface.The tool includes a housing having a handle attached thereto, and astud-receiving means mounted within the housing for holding and ejectinga stud from the tool. The stud-receiving means includes a heater havinga heating element positioned such that heat will reach a coating ofthermoplastic adhesive on the head portion of a stud inserted in thestud-receiving means. The stud-receiving means also includes a lockingdevice for releasably holding the stem portion of a stud in thestud-receiving means. The locking device is actuated to release the studby a trigger and trigger switch positioned in the handle. A spring andpiston arrangement included in the stud-receiving means bears againstthe stem of the stud and ejects the stud with considerable force whenthe locking device has been released. A plurality of electrical contactmeans are mounted in the housing around the periphery of the heater.Each contact means includes a plungerlike device which when depressed bycontact with the mounting surface actuates a control switch. Eachcontrol switch is in turn connected in series with the trigger switchthat releases the locking device holding the stud. Thus, the lockingdevice cannot be released unless the tool is properly positioned withrespect to the mounting surface. When the stud is ejected against a coldsurface the adhesive thereon is spread evenly upon impact because of theejection force and rapid cooling of the adhesive occurs to form a quickbond between the surface and the stud. A heat-sensing device is includedin the tool to monitor the temperature of the head portion of the stud.An adjustable temperature control is also provided so that various heatscan be applied to the head of the stud and thus permit the use ofdifferent adhesives.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a pictorial view of thestud-bonding gun;

FIG. 2 is a cross-sectional side view, partially broken away, of thestud-bonding gun;

FIG. 3 is a cross-sectional view of the stud-receiving means removedfrom the tool and includes the heater, locking device and stud ejectionmeans;

FIG. 4 is a view of the heat-sensing means removed from thestud-receiving means;

FIG. 5 is an enlarged view of the sensing end of the thermocouple probe;

FIG. 6 is a cross-sectional view of the electrical contact means mountedin the housing around the heater;

FIG. 7 is a view taken along lines 7-7 of FIG. 2 that illustrates thetemperature-indicating gage, the temperature regulating device and anon-off switch.

DETAILED DESCRIPTION OF THE INVENTION FIG. I is a pictorial view of thestud-bonding gun consisting of an outer housing It) having a forward orfront cylindrical casing 12 and an enlarged rear casing M to which ahandle 16 is secured by bolts 18 or other suitable means. A trigger i7is mounted in the handle along with a trigger switch 19 (see FIG. 2),electronics package 20 and power cord 21. Casing 12 has an inner housingor casing 22 mounted therein that is concentric to casing l2. Casings 22and 12 form an annular chamber 24 in which three equally spacedelectrical contact devices 26, 28 and 30 are mounted. The function ofthe electrical contact devices will be described in more detailhereinafter. Annular chamber 24 is closed by a closure member 32 whichhas openings formed therein to accommodate the electrical contactdevices.

Centrally mounted within housing I0 is a studreceiving means indicatedgenerally in FIG. 2 by numeral 34. The studreceiving means includes arelatively large disc-shaped housing 36 attached to a smallercylindrical housing 38. Housing 36 is designed to receive the headportion 40 (FIG. 3) of a stud 42 which has a layer 43 of thermoplasticadhesive applied thereto. As can be seen from FIG. 3, stem 44 of thestud is hollow and is positioned within cylindrical housing 38. Aheating device for softening the adhesive is mounted in housing 36 andconsists of a plate 41 having an inwardly tapering surface that conformsto the shape of the head portion of the stud. Resistance heatingelements 43 are encased in a ceramic material which abuts plate 41 so asto facilitate heat transfer therebetween and to the head portion of thestud. A source of electrical current is connected to heating element 43by means of externally threaded electrical connector pins 46 and 48.Plate 4l and ceramic material are insulated from housing 36 by asuitable mounting adhesive 50 and an insulator block 52 which is securedin position by a plate 54 closing one side of housing 36. The elementsjust described all have a central opening therein that forms an opening56 through which the stem portion 44 of the stud can pass. The output ofthe heating device is high enough to accomplish rapid heating of thestud to a temperature required by the adhesive coating.

Housing 38 which accommodates the stem portion of the stud is composedof a forward section 58 and a slightly larger rear section 60. Where thetwo sections meet a shoulder 62 is formed which functions as a stop fora piston 64 slidably mounted in housing 38. Piston 64 has a skirtlikeportion 66 having a diameter substantially equal to that of cylindersection 58 and an outwardly extending flange 68 having a diametersubstantially equal to that of cylinder section 60. Flange 68 abutsshoulder 62 when the piston has been biased to a forward position byspring 70 housed in section 60 of cylinder 38. A hollow cylindrical plug72 closes end 60 of cylinder 38.

A locking device 74 mounted on section 58 of cylinder 38 engages agroove 82 in stem 44 of the stud to hold the stud in a cocked positionand retain piston 66 in a rearwardly or cocked position wherein spring70 is compressed between flange portion 68 of the piston and one end ofcylindrical plug 72. The locking device is a solenoid-actuated mechanismthat is released when electrical current is passed through the solenoidvia connections 76 and 78 (see FIG. 2) and plunger 80 is withdrawn fromgroove 82 in the stud. As is readily apparent, withdrawal of plunger 80releases the stud so that it will be ejected from the stud-receivingmeans by the forward motion of piston 66 due to spring 70 expanding.

A heat-sensing device, like for example a thermocouple probe 84 (seeFIG. 4), is centrally mounted in the stud-receiving means and adapted toenter the hollow stem of the stud. The probe is composed of a longslender tube 86 having two wires 88 and 90 (see FIG. composed ofdissimilar metals, one of iron and one of constantan, extending thelength thereof and embedded in an insulation material 92 filling tube86. The ends of wires 88 and 90 are welded together at one end of tube86 and this weld is surrounded by a heat-conduo tive packing 94 whichalso forms a closure for one end oftube 86. The other end of tube 86 isclosed by means of a base member 96 mounted thereon. A guide member 98is mounted intermediate the ends of tube 86. The tip ofthe probecontaining the welded wires is positioned near the stud head portion forsensing the temperatures thereof.

Base member 96 is slidably mounted in a bore 99 formed in cylindricalplug 72 and guide member 98 is slidably mounted in a bore I00 formed inpiston 64. Bore 100 is closed by a plug 102 threaded into piston 64. Aspring I04 mounted between guide member 98 and plug 102 biases probe 84to a forward position. In the forward position end surface 106 of base96 is spaced away from a microswitch I08 mounted in cylindrical member72. Insertion of the stud into the stud-receiving means results in probe84 being moved to the rear so that surface 106 of base 96 comes intocontact with contact [I0 of microswitch I08. Microswitch 108 isconnected into a circuit with heating element 42 so that the heatercannot be activated unless the stud has been fully inserted into thestud-receiving means. Electrical leads I12 and 114, extensions of wires88 and 90, are connected to a suitable temperature readout devicediscussed hereafter.

As mentioned above, proper positioning of the tool is assured by meansof electrical contact devices 26, 28 and mounted in housing 12 in aspaced relation about the periphery of disc-shaped housing 36surrounding the studhealing device. Each electrical contact means, asshown in FIG. 6. consists of a tubular housing l 16 having anothertubular housing 118 mounted in one end thereof. Housing [16 has a bore120 formed therein in which a pistonlike member I22 is slidably mounted.A plunger I24 is slidably mounted in member I22 and guided in itsmovement through bore 120 by means of a guide member 126 intermediatethe ends thereof. A spring 128 mounted on plunger 124 between guide 126and the end of piston I22 normally maintains plunger I24 in the positionshown in FIG. 6. Plunger 124 has an end portion 130 which extendsoutwardly to a position in front of housing 10 as shown in FIG. I. Whenplunger end portion 130 is pushed to the rear against the action ofspring 128 it tends to push piston 122 to the rear to actuatemicroswitch 132 mounted in casing 118. Each of the three spacedelectrical contact devices includes a microswitch and all three of thesemicroswitches are connected in series with trigger l6 and the solenoidof locking device 74 shown in FIG. 4. This is so that the stud cannot bereleased from the stud-receiving means until the stud-bonding gun hasbeen properly positioned with respect to a surface on which it is to bemounted.

FIG. 7 is a view taken along lines 7-7 of FIG. 2 illustrating a plate134 which forms a closure for housing 10. Plate 134 also provides amounting surface for a temperature-indicating instrument I36 connected(not shown) to the heat-sensing probe. The instrument could be anygalvanometer or potentiometer-type instrument adapted for use with athermocouple probe and capable of reading out temperature. An adjustabletemperature control mechanism I38, a potentiometer or other suitabledevice. is mounted in plate 134 and also connected to the heater (notshown) for controlling the amount of heat applied to the stud headportion. Immediately below mechanism I38 is an on-off switch 140, alsoconnected to the heater by circuitry not shown herein, that the user ofthe tool actuates to turn the heater on or off.

The operation of the tool will now be discussed, assuming that the toolis in the grasp of a user and that the power cord has been connected toa suitable source of power and the user has a supply of studs availableto him with adhesive on the head portions thereof. A stud is insertedinto the stud-receiving means so that the head portion abuts thetapering surface of plate 40 of the heating device. In this positiongroove 82 in the stem of the stud will be engaged by plunger 80 oflocking device 74 and the stud will be held in the tool. Inserting thestud will also move piston 64 to the rear compressing spring 70. Theuser will turn the gun on with onoff switch to start the heating andthen position the tool with respect to the surface on which a stud is tobe mounted. When the tool has been properly positioned the plunger 130in each of the electrical contact devices will be depressed to actuatethe microswitch in each contact device, so as to activate the circuitcontaining the trigger switch. As was discussed above, no current canflow to the trigger until all three of the microswitches in theelectrical contact devices have been closed. When, as indicated by thetemperature readout device 136, the head portion of the stud has beenheated to a point wherein the adhesive applied thereto is ready for use,the user will depress trigger 17 to close trigger switch I9 and therebyapply power to locking device 74 to retract plunger 80 from groove 82 inthe stem of the stud. When the stud is released piston 64 will be drivenforward by spring 70 to eject the stud from the stud-bonding tool. Thestud will strike the surface on which it is to be mounted withconsiderable force and this results in an even spreading of the adhesiveover both of the surfaces to be joined. The mounting surface is cold andthere results a rapid transfer of heat away from the stud that cools theadhesive and makes a quick bond between the stud and the mountingsurface.

This completes the detailed description of the invention. While apreferred embodiment has been described there will be many variationswhich can be made to the invention. The exact circuitry employed in thedevice has not been described in detail herein because such circuitrycould vary considerably depending upon how sophisticated the tool was tobe constructed. For example, it may well be for some applications that avery precise temperature control would be required and therefore a morecomplicated temperature adjustment mechanism 138 made up of severalcomponents might be required. The same would hold true for thetemperature-indicating mechanism 136 and for all of the other componentsused in the tool. Thus, the circuitry would vary with the selection ofcomponents. In any event the actual circuit design for connecting thevarious components of the tool would be well within the skill ofacompetent electronics technician.

What we claim is:

l. A tool for mounting a stud having a hollow stem and a head portionwith a coating of thermoplastic adhesive applied thereto to a mountingsurface by bonding the adhesive-coated head portion of the stud to themounting surface, said tool comprising:

an outer housing adapted to be held in a person's hand;

a stud-receiving means mounted in said outer housing for holding thestud, said stud-receiving means including a heater means for heating thehead of the stud to soften the adhesive and an ejection means fordirecting the heated head portion of the stud against the mountingsurface, whereby the heated thermoplastic adhesive will adhere to themounting surface and form a permanent bond when the thermoplasticadhesive cools and solidifies; and

electrical control means mounted in said tool for controlling saidheater means and said ejection means, said electrical control meanscomprising contact means mounted in said outer housing and actuated bycontact with the mounting surface, said contact means operating toeffectively inactivate said electrical control means unless the contactmeans are in engagement with the mounting surface.

2. The tool recited in claim 1 wherein said stud-receiving meansincludes:

a disclike housing mounted in said outer housing so as to surround andabut a stud positioned in said stud-receiving means. said disclikehousing having said heater means mounted therein for applying heat tothe stud so as to soften the thermoplastic adhesive on the stud; and

a cylindrical housing mounted to said disclike housing for receiving thestern of the stud and housing said ejection means.

3. The tool recited in claim 2 wherein:

said cylindrical housing has a reduced inside diameter at a pointintermediate the ends thereof and an inwardly projecting shoulder atthat intermediate point, whereby two bores of different diameter areformed in said cylindrical housing, that end of said cylindrical housinghaving the reduced inside diameter being connected to said disclikehousing;

a cylindrical member having an internal bore substantially smaller thaneither of those in said cylindrical housing fixedly mounted in the otherend of said cylindrical housing and forming a substantial closuretherefor;

a pistonlike member slidably mounted in said cylindrical housing forengagement with the stern of a stud held therein, said pistonlike memberhaving an annular flange formed on one end thereof that abuts theinwardly pro jecting shoulder in said cylindrical housing at one extremeof its travel; and 7 spring means positioned between said pistonlikcmember and said cylindrical member that exerts a force tending to biassaid pistonlike member toward said inwardly projecting shoulder. wherebyan ejecting force will be applied to a stud held in said stud-receivingmeans.

4. The tool recited in claim 3 which further includes:

locking means mounted on said cylindrical housing for releasableengagement with the stem of said stud to lock said pistonlike member ina cocked position wherein said spring means i compressed.

5 The tool recited in claim 4 wherein said stud-receiving means furtherincludes a rod-shaped heat-sensing element centrally mounted in saidcylindrical housing and slidably mounted through said pistonliltemember, said heat-sensing element having one end thereof extending intothe hollow stem of said stud to a position ad acent the head portionthereof for sensing the temperature of the head portion.

6. The tool recited in claim 5 wherein:

a base member is mounted on the other end of said rodshaped heat-sensingelement and positioned for slidable movement in said cylindrical member;

a switch means mounted in said cylindrical member that is contacted bysaid base member when the rod-shaped heat-sensing element is movedrearwardly in response to a stud being inserted in said stud-receivingmeans.

7. The tool recited in claim 6 which further includes:

a large handle connected to said outer housing for facilitating use ofthe tool; and

a hand-operated trigger switch mounted in said handle.

8. The tool recited in claim 7 which further includes a temperature gagefor reading out the temperature of the stud head portion.

9. The tool recited in claim 8 which further includes an adjustabletemperature control means for controlling the amount of heat applied tothe stud head portion.

1. A tool for mounting a stud having a hollow stem and a head portionwith a coating of thermoplastic adhesive applied thereto to a mountingsurface by bonding the adhesive-coated head portion of the stud to themounting surface, said tool comprising: an outer housing adapted to beheld in a person''s hand; a stud-receiving means mounted in said outerhousing for holding the stud, said stud-receiving means including aheater means for heating the head of the stud to soften the adhesive andan ejection means for directing the heated head portion of the studagainst the mounting surface, whereby the heated thermoplastic adhesivewill adhere to the mounting surface and form a permanent bond when thethermoplastic adhesive cools and solidifies; and electrical controlmeans mounted in said tool for controlling said heater means and saidejection means, said electrical control means comprising contact meansmounted in said outer housing and actuated by contact with the mountingsurface, said contact means operating to effectively inactivate saidelectrical control means unless the contact means are in engagement withthe mounting surface.
 2. The tool recited in claim 1 wherein saidstud-receiving means includes: a disclike Housing mounted in said outerhousing so as to surround and abut a stud positioned in saidstud-receiving means, said disclike housing having said heater meansmounted therein for applying heat to the stud so as to soften thethermoplastic adhesive on the stud; and a cylindrical housing mounted tosaid disclike housing for receiving the stem of the stud and housingsaid ejection means.
 3. The tool recited in claim 2 wherein: saidcylindrical housing has a reduced inside diameter at a pointintermediate the ends thereof and an inwardly projecting shoulder atthat intermediate point, whereby two bores of different diameter areformed in said cylindrical housing, that end of said cylindrical housinghaving the reduced inside diameter being connected to said disclikehousing; a cylindrical member having an internal bore substantiallysmaller than either of those in said cylindrical housing fixedly mountedin the other end of said cylindrical housing and forming a substantialclosure therefor; a pistonlike member slidably mounted in saidcylindrical housing for engagement with the stem of a stud held therein,said pistonlike member having an annular flange formed on one endthereof that abuts the inwardly projecting shoulder in said cylindricalhousing at one extreme of its travel; and spring means positionedbetween said pistonlike member and said cylindrical member that exerts aforce tending to bias said pistonlike member toward said inwardlyprojecting shoulder, whereby an ejecting force will be applied to a studheld in said stud-receiving means.
 4. The tool recited in claim 3 whichfurther includes: locking means mounted on said cylindrical housing forreleasable engagement with the stem of said stud to lock said pistonlikemember in a cocked position wherein said spring means is compressed. 5.The tool recited in claim 4 wherein said stud-receiving means furtherincludes a rod-shaped heat-sensing element centrally mounted in saidcylindrical housing and slidably mounted through said pistonlike member,said heat-sensing element having one end thereof extending into thehollow stem of said stud to a position adjacent the head portion thereoffor sensing the temperature of the head portion.
 6. The tool recited inclaim 5 wherein: a base member is mounted on the other end of saidrod-shaped heat-sensing element and positioned for slidable movement insaid cylindrical member; a switch means mounted in said cylindricalmember that is contacted by said base member when the rod-shapedheat-sensing element is moved rearwardly in response to a stud beinginserted in said stud-receiving means.
 7. The tool recited in claim 6which further includes: a large handle connected to said outer housingfor facilitating use of the tool; and a hand-operated trigger switchmounted in said handle.
 8. The tool recited in claim 7 which furtherincludes a temperature gage for reading out the temperature of the studhead portion.
 9. The tool recited in claim 8 which further includes anadjustable temperature control means for controlling the amount of heatapplied to the stud head portion.